Goettl
duct structure



Sept. 20, 1966 w. H. GOETTL 3,273,598

DUCT STRUCTURE Filed March 23, 1964 4 Sheets-Sheet 1 i INVENTOR.

/ WILLIAM a eosrn.

Sept. 20, 1966 w. H. GOETTL 3,

DUCT STRUCTURE Filed March 23, 1964 4 Sheets-Sheet 2 INVENTOR.

WILLIAM H. GOET TL Sept. 20, 1966 w. H. GOETTL 3,273,598

DUCT STRUCTURE Filed March 23, 1964 4 Sheets-$heet 5 INVENTOR.

WILLIAM H. GOETTL Sept. 20, 1966 w. H. GOETTL 3,273,598

nucw STRUCTURE Filed March 25, 1964 4 Sheets-Sheet 4 INVENTOR.

WILLIAM H. GOETTL United States Patent Ofiice 3,273,598 Patented Sept. 20, 1966 3,273,598 DUCT STRUCTURE William H. Goettl, 4627 N. Granite Reef Road, Scottsdale, Ariz. Filed Mar. 23, 1964, Ser. No. 353,842 8 Claims. (Cl. 138--37) This invention relates to a duct structure and more par ticularly to a duct structure for use in air conditioning systems or the like wherein two flow passages are contained in a common duct and wherein these flow passages may be angularly displaced or rotated within the duct so that the relative disposition of the passages may communicate with any one of four sides of a duct as desired, thereby permitting the installation of equipment in connection with the ducts in such a manner as to switch the locations of the passages with respect to equipment coupled thereto,

This application discloses improvements upon the invention disclosed in my copending application for Duct Structure, Serial No. 281,841, filed May 20, 1963.

In the installation of air conditioning ducts it has been a problem, for example, to provide a common duct having two flow passages for the delivery of refrigerated air from a refrigeration unit and for the return of room air thereto; said problem most commonly existing in the mechanical disposition of the refrigeration unit with respect to the ducting so that the delivery and return air duct sections of a refrigeration unit coincident with the passages in the air conditioning duct and yet permit convenient installation of the refrigeration unit.

In many instances where ducts are used for air conditioning purposes they contain two parallel passages and oftentime these passages extend through walls or between walls and it is desired to provide for return air and air delivery grills in various horizontal or vertical orientation in order to accommodate the physical features of a building structure.

Various roof mounted refrigeration systems have been used for air conditioning and these systems include cool air delivery duct sections as well as return sections which are normally coupled to a common duct having separate flow passages, these flow passages are appropriately connected to grills for the delivery of cold air into a room and for the return of air to the refrigeration unit. After the ducts have been installed in the building, the refrigeration unit may subsequently be installed, but it may be found that due to interference with the roof top or some other feature of the building the air conditioning unit cannot be installed on the duct conveniently so that the duct passages coincide to permit the return air duct section to communicate properly with the return duct section of the unit and to permit the cool air delivery duct section to communicate with the cold air delivery section of the refrigeration unit.

Accordingly, it is an object of the present invention to provide a duct structure which is particularly adapted for use in buildings and in connection with air conditioning systems therein for the purpose of conveniently orienting inlet and outlet grills in adjacent rooms having different angularly disposed air delivery and return axes.

Another object of the invention is to provide a duct structure having substantially rectangularly cross section and provided with separate duct sections separated by baffle structures which are disposed angularly to twist the duct passage either 90' or 180 degrees so that the relative disposition of two duct passages in the duct structure may be changed 90 degrees or 180 degrees as desired.

Another object of the invention is to provide a very simple duct and battle structure wherein a single sheet of metal separates two flow passage portions in the duct section and wherein said single sheet bafiie section is formed into two integral portions, one of which is a triangle and another of which is trapezoidal and whereby two of the single sheets, each having a triangular and trapezoidal portion, are connected together to form a baflle structure which turns degrees within said duct section.

Another object of the invention is to provide a novel duct structure which is substantially rectangular in cross section and wherein a novel baffie structure extends across the interior of the duct from side to side to provide two duct flow passages and wherein the baffle structure comprises a pair of sheet metal plates connected together to form a 90 degree rotational turn of the separate flow passages in the duct, each of said plates having a triangular port-ion extending from side to side across the interior of the duct and each plate also having an integral trapezoidal portion disposed at a compound angle with respect to the cross section of the duct, thereby providing a very simple means for turning a pair of flow passages in a duct and which structure may readily be made on a conventional sheet metal brake.

Another object of the invention is to provide a novel duct structure composed of a plurality of duct sections and angular baflles therein, said duct sections coupled together in a unitary structure and readily insertably in a conventional duo passage duct system for exchanging the horizontal or vertical disposition of rectangular in cross section passages in the duct or for switching these passages rotationally degrees, as desired, for the purpose of accommodating the desired locations of equipment disposed at opposite end of an air conditioning duct.

Further objects and advantages of the invention may be apparent from the following specification, appended claims and accompanying drawings, in which:

FIG. 1 is an end perspective view of a duct structure in accordance with the present invention and showing fragmentarily a duplicate structure in connection therewith;

FIG. 2 is a view similar to FIG. 1, showing angular bafile structure of the duct structure disclosed in FIG. 1 and showing in phantom by broken lines the outside duct section structure of the invention;

FIG. 3 is an end view of the duct structure of the invention;

FIG. 4 is a sectional view taken from the line 44 of FIG. 3, showing the baffle structure of the invention;

FIG. 5 is an exploded view taken from the line 5-5 of FIG. 4, showing the one piece baflle members, disclosed in FIG. 4, separated to amplify the illustration;

FIG. 6 is a view of the exploded baflle structures taken from the line 66 of FIG. 5;

FIG. 7 is a view of a flat blank from which one of the baflle structures of the invention is formed;

FIG. 8 is an enlarged fragmentary sectional view taken from the line 88 of FIG. 1;

FIG. 9 is an enlarged fragmentary sectional view taken from the line 9-9 of FIGS. 1 and 2 of the drawings;

FIG. 10 is a fragmentary view of a building structure showing a duct structure of the present invention installed therein and illustrating the duct structure connected to an air conditioner and showing by broken lines the facility of moving the air conditioner around 180 degrees with relation to the axis of the duct structure in accordance with the convenience of the twisted passage structure of the present invention;

FIG. 11 is a fragmentary sectional view of a building structure showing a dual passage air conditioning duct installed horizontally therein and wherein the dual passages are separated by an intermediate vertically disposed baffle;

FIG. 12 is another view similar to FIG. 11, but showing a dual passage duct structure having a horizontally disposed b-afiie separating a pair of duct passages in the duct, thereby illustrating the possibility of axial rotation of the passage structures substantially 90 degrees from the disclosure of FIG. 11 to the disclosure of FIG. 12, in accordance with the invention;

FIG. 13 is a view of a pair of the baflle plates of the invention taken from the line 13-13 of FIG. 2;

FIG. 14 is an enlarged fragmentary sectional view taken from line 1414 of FIG. 13; and

FIG. 15 is an enlarged fragmentary sectional view taken from line 1515 of FIG. 13.

As shown in FIGS. 1 and 2 of the drawings, the duct structure of the present invention includes a duct section 20 which is substantially rectangular in cross section having normally upper and lower sides 22 and 24, respectively, which are substantially parallel with each other and a pair of substantially vertical sides connected therewith designated 26 and 28, respectively, all of which form a rectangular in cross sectional duct structure.

As shown in FIG. 7 of the drawings, baflle sections are disposed in each duct section 20 and these bafile sections, as shown in FIG. 7, are made of a single piece of sheet metal designated 30. This metal is broken at breaklines 32, 34, 36, 38 and 40 to outline one triangular section 42 and one trapezoidal section 44.

Adjacent the break lines 36, 38 and 40 are flanges 46, 48 and 50, respectively, which are disposed to connect the baffle structure with the inner walls of the duct sides 22, 24, 26 and 28 and with respective edge portions 52 of adjacent triangular sections 42.

Adjacent the break line 32 is a flange 54 which is adapted to interconnect passages dividing baflles of adjacent duct sections 20 which are axially connected together, as shown in FIG. 1 of the drawings, and which will be hereinafter described in detail.

As shown in FIG. 1 of the drawings, a baffie structure separates the duct 20 into two separate flow passages 56 and 58 which are disposed on opposite sides of one Otf the triangular portions 42 of the baffle structure. These triangular portions 42 extend across the duct structure and have planes which are substantially parallel to opposite sides of the rectangular in cross section duct structure.

Connected to an edge 52 of one of the duct sections is a complemental flange 46 of one of the trapezoidal sections, as will be hereinafter described, all of which forms a 90 degree rotational transition of the bafile structure in the duct 20. The flange 46 of one of the trapezoidal sections is spot welded to the respective edge 52 of the triangular section 42, all as shown best in FIG. 1 of the drawings.

This may also be clear from an inspection of FIG. 2 of the drawings, wherein the duct structure is broken away to expose the baflles internally thereof. As shown in FIG. 2 of the drawings, it will be seen that the flange 50 of the trapezoidal section 44 is connected to the top 22 of the duct structure by means of spot welds 60 and that the flange 48 of the baffle section 30 at another edge of the trapezoidal portion 44 is connected by spot welds 62 to the side 26 of the duct 20, shown in FIGS. 1 and 2 of the drawings.

It will be seen that the disclosure of FIG. 3 shows an opposite end of the duct and baffle structure from that shown in FIG. 2. Thus, FIG. 3 discloses the structure as viewed in a direction of the arrow A in FIG. 2 of the drawings, where-in one triangular section 42 of one of the baffle members is disposed horizontally. Thus, the triangular section 42, shown in FIG. 3, is disposed 90 degrees from the triangular section 42, most plainly shown in FIG. 2 of the drawings.

Accordingly the duct passages 56 and 58 are rotated 90 degrees from the disclosure oat FIGS. 1 and 2 to the disclosure of FIG. 3. As for example, the duct passage 56 at one end of the duct 20 is disclosed adjacent the wall 28 and at the opposite end of the duct 20, as shown in FIG. 3, the duct passage 56 is adjacent the wall 22. Likewise, the duct passage 58, shown in FIG. 1 of the drawings, adjacent the wall 26 is disposed at the opposite end of the duct section 20 adjacent the lower wall 24 of the duct section 20. The triangular portions 42 of the bafile sections 30 are disposed to divide the flow passage sections and extend at degrees to opposite sides of the duct section 20 while the trapezoidal sections 44 extend at compound angles with respect to lateral and longitudinal axes of the duct 20.

As shown in FIG. 4 of the drawings, spot welds 66 connect a respective edge 52 of one of the triangular baflie sections with a respective flange 46 of a trapezoidal section 44.

As shown in FIGS. 5 and 6 of the drawings, due to the direction in which the views are taken, the exploded view of the baffle plates 30 is such as to disclose them substantially upside down, as shown in FIG. 1 of the drawings, but arranged in an axial end view similar to that shown in FIG. 3.

It will be seen that each baflle section, as shown in FIG. 7, includes a triangular section 52 and a trapezoidal section 44, each trapezoidal section 44 at its flanges 46 is spot welded to a complemental edge portion 52 of each triangular section 42 by means of spot welds 66, thus, each 90 degree section involving a pair of the baflle plates 30 includes a connection of each flange 46 of each trapezoidal section 44 with a complemental edge 52 of a triangular section 42. Thus, there are two flanges 46 and two edges 52 which are connected together by spot welds 60 and each bafile section 30, thus, contributes substantially 45 degrees to the turning of the structure whereby two of the baffle sections 30, thus, connected as shown herein provides a bafile structure which turns the passage sections 56 and 58 in the duct 20 substantially 90 degrees.

It will be seen [from a disclosure of FIGS. 13, 14 and 15 that the flange portions 46 of each trapezoidal section 44 of each baflle section 30 extend into connection with a respective edge 52 of each of the triangular portions 44 and in the assembly of two of these bafile sections 30, as shown in FIG. 13, the triangular flanges 46 extend in opposite directions to each other and their respective break lines 36 are disposed almost in alignment with each other and, also, that the edge portions 52 of the triangular portions 42 are almost in alignment with each ot er.

Each duct section 20 at the ends of its sides 26 and 28 is provided a hook flange portion 70, shown best in FIGS. 1 and 4 of the drawings. Each hook portion 70 of adjacent duct walls 26 is opposed to the adjacent hook portion 70 so that a channel shaped clip 72 may be slid'ably engaged thereover to hold the respective adjacent duct sections 20 together. Accordingly, it will be appreciated that the baffle structure in each duct section 20 may rotate the flow passages 56 and 58, 90 degrees so that two of the duct sections 20 connected end to end will rotate the flow passages 100, degrees.

The upper and lower walls 22 and 24 of the duct 20 are connected by an S-shaped clip 74 which embraces overlapping edges 76 of these walls 22 and 24. Thus, the duct sections 20 are held together in end to end commumcative relationship with each other. It will also be noted that the end flanges 54 of the triangular baffle sections 42 are also connected by an S-shape'd clip 74, as indicated by the section line 99 in FIG. 2, whereas the section line 99 of FIG. 1, indicates the same S-shaped clip structure 74 for connecting a pair of the outer opposed walls 22 and 24 of adjacent duct sections 20.

As shown in FIG. 10 of the drawings, an air conditioner 82 may conveniently'be installed in a solid line position, as shown, rather than in a broken line position 88 which would normally interfere with the gable 90 of the building roof. The duct sections 20 installed in connection with the inlet 86 and outlet 84 of the air conditioner 82 permit the air conditioner 82 to be installed in the solid line position and, thus, the duct passages 56 and 58 are rotated substantially 180 degrees from their position in the wall 80, all as shown in FIG. of the drawings. This facility, thus, permits a low mounting of the air conditioner 82 and permits it to be installed so that it doesnt interfere with the gable 90 in accordance with preinstalled duct structures having the passages 56 and 58 oriented in the wall 80, as shown. This situation occurs in many instances and in such instances the basic duct work has already been installed in the home before the customer decides what type of air conditioner he needs and what its configuration will be. When the some is sold, the final installation takes place and it is oftentimes necessary to rotate the passages in order to afford the convenience in the unobstructed installation of the air conditioner, all as illustrated in FIG. 10 of the drawings.

The passages 56 and 58 installed in a wall section 80, as shown in FIG. 11 of the drawings, may be rotated substantially 90 degrees to a position, as shown in FIG. 11 of the drawings, to provide for convenience of inlet and outlet grills on opposite sides of the wall structure 80. Accordingly, one duct section 20, in accordance with the present invention, may be utilized to rotate the passages 56 and 58 from the position, as shown in FIG. 11, to the position, as shown in FIG. 12, thus, the 90 degree rotation affords the possibility of opposed inlets and outlets on opposite sides of the wall 80 communicating with both of the passages 56 and 58.

It will be obvious to those skilled in the art that various modifications of the present invention may be resorted to in a manner limited only by a just interpretation of the following claims.

I claim:

1. In a dual passage duct structure the combination of 2 a rectangular in cross section hollow duct structure having four sides and having two passages therein; a baffle separating said passages; first and second sheet metal baflle plates of said baffie; each of said bafile plates comprising a triangular section and a trapezoidal section; an edge of each trapezoidal section connected to an edge of each triangular section of each baffie plate; each trapezoidal section disposed at an angle to each triangular section of each baffle plate whereby said edge of each trapezoidal section is connected to a respective edge of each triangular section to provide a 90 degree twist in the baffle structure formed by the two plates; each triangular section being disposed at right angles to two opposite sides of said rectangular in cross section duct structure; one of said triangular portions of one of said plates being disposed at 90 degrees to a respective triangular portion of the other baffle plate.

2. In a dual passage duct structure the combination of: a rectangular in cross section hollow duct structure having four sides and having two passages therein; a batfie separating said passages; first and second sheet metal bafile plates of said baffle; each of said baffle plates comprising a triangular section and a trapezoidal section; an edge of each trapezoidal section connected to an edge of each triangular section of each bafile plate; each trapezoidal section disposed at an angle to each triangular section of each bafile plate whereby said edge of each trapezoidal section is connected to a respective edge of each triangular section to provide a 90 degree twist in the baffle structure formed by the two plates; each triangular section being disposed at right angles to two opposite sides of said rectangular in cross section duct structure; one of said triangular portions of one of said plates being disposed at 90 degrees to a respective triangular portion of the other baffie plate; a second edge portion of each trapezoidal section being connected to a side wall of said duct structure disposed in a plane degrees to the triangular section of the respective baffle plate.

3. In a dual passage duct structure the combination of: a rectangular in cross section hollow duct structure having four sides and having two passages therein; a baffle separating said passages; first and second sheet metal bafi'le plates of said baflle; each of said baffie plates comprising a triangular section and a trapezoidal section; an edge of each trapezoidal section connected to an edge of each triangular section of each bafile plate; each trapezoidal section disposed at an angle to each triangular section of each baffle plate whereby said edge of each trapezoidal section is connected to a respective edge of each triangular section to provide a 90 degree twist in the bafile structure formed by the two plates; each triangular section being disposed at right angles to two opposite sides of said rectangular in cross section duct structure; one of said triangular portions of one of said plates being disposed at 90 degrees to a respective triangular portion of the other baffle plate; -a second edge portion of each trapezoidal section being connected to a side wall of said duct structure disposed in a plane 90 degrees to the triangular section of the respective :bafile plate; a third edge portion of said trapezoidal section secured to a wall of said duct structure disposed parallel to the triangular portion of the respective bafile plate.

4. In a dual passage duct structure the combination of: a rectangular in cross section hollow duct structure having four sides and having two passages therein; a baflle separating said passages; first and second sheet metal baflle plates of said baffle; each of said baffle plates comprising a triangular section and a trapezoidal section; an edge of each trapezoidal section connected to an edge of each triangular section of each bafi le plate; each trapezoidal section disposed at an angle to each triangular section of each bafile plate whereby said edge of each trapezoidal section is connected to a respective edge of each triangular section to provide a 90 degree twist in the baffie structure formed by the two plates; each triangular section being disposed at right angles to two opposite sides of said rectangular in cross section duct structure; one of said triangular portions of one of said plates being disposed at 90 degrees to a respective triangular portion of the other bafile plate; a second edge portion of each trapezoidal section being connected to a side wall of said duct structure disposed in a plane 90 degrees to the triangular section of the respective baffle plate; a third edge port-ion of said trapezoidal section secured to a wall of said d-uct structure disposed parallel to the triangular portion of the respective baffle plate; one edge of said triangular portion extending outwardly and disposed from one side of said duct structure to an opposite side thereof and separating the duct cross section into two flow passages at one end thereof.

5. In a dual passage duct structure the combination of: a rectangular in cross section hollow duct structure having four sides and having two passages therein; a balfie separating said passages; first and second sheet metal bafile plates of said baflle; each of said baffle plates comprising a triangular section and a trapezoidal section; an edge of each trapezoidal section connected to an edge of each triangular section of each bafile plate; each trapezoidal section disposed at an angle to each triangular section of each baffle plate whereby said edge of each trapezoidal section is connected to a respective edge of each triangular section to provide a 90 degree twist in the bafile structure formed by the two plates; each triangular section being disposed at right angles to two opposite sides of said rectangular in cross section duct structure; one of said triangular portion of one of said plates being disposed at 90 degrees to a respective triangular portion of the other bafile plate; a second edge portion of each trapezoidal section being connected to a side wall of said duct structure disposed in a plane 90 degrees to the triangular section of the respective bafile plate; a third edge portion of said trapezoidal section secured to a wall of said duct structure disposed parallel to the triangular portion of the respective baffle plate; one edge of said triangular portion extending outwardly and disposed from one side of said duct structure to an opposite side thereof and separating the duct cross section into two flow passages at one end thereof; a pair of said rectangular in cross section hollow duct structures connected end to end to each other; and means interconnecting the last mentioned edges of adjacent triangular sections of said bafile structures.

6. In a dual passage duct structure the combination of: a rectangular in cross section hollow duct structure having four sides and having two passages therein; a bafi le separating said passages; first and second sheet metal bafile plates of said baffie; each of said bafile plates comprising a triangular section and a trapezoidal section; an edge of each trapezoidal section connected to an edge of each triangular section of each bafiie plate; each trapezoidal section disposed at an angle to each triangular section of each baffle plate whereby said edge of each trapezoidal section is connected to a respective edge of each triangular section to provide a 90 degree twist in the baffle structure formed by the two plates; each triangular section being disposed at right angles to two opposite sides of said rectangular in cross section duct structure; one of said triangular porti-ons of one of said plates being disposed at 90 degrees to a respective triangular portion of the other bafile plate; a second edge portion of each trapezoidal section being connected to a side wall of said duct structure disposed in a plane 90 degrees to the triangular section of the respective baffie plate; a third edge portion of said trapezoidal section secured to a wall of said duct structure disposed parallel to the triangular portion of the respective bafile plate; one edge of said triangular portion extending outwardly and disposed from one side of said duct structure to an opposite side thereof and separating the duct cross section into two flow passages at one end thereof; a pair of said rectangular in cross section hollow duct structures connected end to end to each other; and means interconnecting the last mentioned edges of adjacent triangular sections of said bafile structures; adjacent ends of said duct structures having hook shaped flanges; and channel structures having opposed portions engaging said hook shaped flanges for holding said duct structures in end to end connected relationship to each other.

7. In a dual passage duct structure the combination of: a rectangular in cross section hollow duct structure having four sides and having two substantially rectangular flow passages therein; a baffle separating said passages; first and second sheet metal baffle plates of said baifie, each of said plates having integral triangular and trapezoidal portions broken at an angle to each other; one edge of said triangular portion of each plate extending across said hollow duct structure from one side to the other thereof and dividing the cross section of the duct into said two passages; each trapezoidal portion of each of said plates disposed at an angle to the sides of said duct structure; a first edge of each trapezoidal section secured to one edge of each respective triangular portion of each of said plates; said edges of two connected plates extending in substantially opposite directions and in substantial alignment with each other at their breaks with the respective trapezoidal sections whereby two triangular sections of said plates and their respective trapezoidal sections when connected together create a substantially degree rotational baffle structure in said duct structure whereby one of said triangular portions is disposed at 90 degrees to a triangular portion of the respective second bafile plate so that one of said triangular portions extends across said duct structure normal to one pair of said sides and the other triangular portion extends across said duct structure at 90 degrees thereto and normal to the two remaining sides disposed at 90 degrees to the first mentioned pair of sides.

8. In a dual passage duct structure the combination of: a rectangular in cross section hollow duct structure having four sides and having two passages therein; a battle separating said passages; first and second sheet metal bafile plates of said baffle; each of said baflle plates comprising a triangular section and a trapezoidal section; an edge of each trapezoidal section connected to an edge of each triangular section of each bafile plate; each trapezoidal section disposed at an angle to each triangular section of each baffle plate whereby said edge of each trapezoidal section is connected to a respective edge of each triangular section to provide a 90 degree twist in the baffie structure formed by the two plates; each triangular section being disposed at right angles to two opposite sides of said rectangular in cross section duct structure; one of said triangular portions of one of said plates being disposed at 90 degrees to a respective triangular portion of the other bafile plate; flange portions of one of said plates disposed in overlapped connected relation to the other of said plates at adjacent edges of said triangular and trapezoidal sections.

References Cited by the Examiner UNITED STATES PATENTS 1,974,109 9/1934 Higley 138-39 1,974,110 9/1934 Higley 138-39 2,183,174 12/1939 Smith 138-39 2,284,937 6/1942 Wood 13837 X 2,292,246 8/1942 Stefifens 13839 LAVERNE D. GEIGER, Primary Examiner.

T. MOORHEAD, Examiner. 

1. IN A DUAL PASSAGE DUCT STRUCTURE THE COMBINATION OF: A RECTANGULAR IN CROSS SECTION HOLLOW DUCT STRUCTURE HAVING FOUR SIDES AND HAVING TWO PASSAGES THEREIN; A BAFFLE SEPARATING SAID PASSAGES; FIRST AND SECOND SHEET MATEL BAFFLE PLATES OF SAID BAFFLE; EACH OF SAID BAFFLE PLATES COMPRISING A TRIANGULAR SECTION AND A TRAPEZOIDAL SECTION; AN EDGE OF EACH TRAPEZOIDAL SECTION CONNECTED TO AN EDGE OF EACH TRIANGULAR SECTION OF EACH BAFFLE PLATE; EACH TRAPEZOIDAL SECTION DISPOSED AT AN ANGLE TO EACH TRIANGULAR SECTION OF EACH BAFFLE PLATE WHEREBY SAID EDGE OF EACH TRAPEZOIDAL SECTION IS CONNECTED TO A RESPECTIVE EDGE OF EACH TRIANGULAR SECTION TO PROVIDE A 90 DEGREE TWIST IN THE BAFFLE STRUCTURE FORMED BY THE TWO PLATES; EACH TRIANGULAR SECTION BEING DISPOSED AT RIGHT ANGLES TO TWO OPPOSITE SIDES OF SAID RECTANGULAR IN CROSS SECTION DUCT STRUCTURE; ONE OF SAID TRIANGULAR PORTIONS OF ONE OF SAID PLATES BEING DISPOSED AT 90 DEGREES TO A RESPECTIVE TRIANGULAR PORTION OF THE OTHER BAFFLE PLATE. 